This invention concerns a method of producing and an apparatus for processing semiconductor devices, as well as an evacuating apparatus for use in the processing apparatus. More spcecifically, this invention concerns a technic for forming a high vacuum by using an oil-free vacuum pump, which is effective, for example, when utilized upon applying various kinds of processings to wafers in a vacuum atmosphere in the production of semiconductor devices.
There has been known a vacuum CVD apparatus for depositing polysilicon on wafers in the production of semiconductor devices, in which a process tube containing wafers are evacuated to a high vacuum degree by using a rotational oil pump and then monosilane (SiH.sub.4) gas is supplied in a great amount at high temperature.
The vacuum CVD technic is described, for example, in "Electronic Material, November 1985, special edition: p58-p59" published from Kabushiki Kaisha Kogyo Chosakai,